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  • Author Author: Workshopshed
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BeagleBone Blue - Music Player

Workshopshed

When I was sent the BeagleBone Blue board my first thought was what could I build that needed 8 servos. I'd seen some fun examples in the MusicTech challenge so a music player seemed like a good idea. I bought some small servos, a glockenspiel (which has metal bars vs a xylophone which has wooden bars) and some wooden balls.

The balls were drilled and mounted on some short dowels made from lollipop sticks. These were attached to the servos using rubber bands, this has two reasons firstly it allows me to undershoot on positioning the servos causing the beater to hit the bar and recoil. It also reduces the risk of the servo stalling if there is a software problem.

 

I initially tried mounting the servos on a block of wood. This proved troublesome and it was not possible to adjust the position or angle of the servos. So a bracket was designed to support the servos. @PiTutorials suggested adding slot for the cable into my design but I found that was not necessary because of the way I was mounting the servos.

 

For the software, I thought I'd try out MQTT as an approach for getting the commands from the UI to the board. This turned out to be very straight forward, I installed Mosca on the BeagleBone and then wrote a client using Paho to communicate to that via WebSockets.

So that I did not need to run all of my code as root, I wrote a "ServoDaemon" that listened for servo positions on a named pipe.

https://github.com/Workshopshed/musicController

 

The power to the servos caused me an issue, the board could not supply enough current to all of the servos. People have reported that the board won't even boot if you try to power more than 6. On the recommendation of the forum, I decided to power the servos from an external supply. This was done by building a small adapter that mimiced the servo pins. Two sockets slid over the outer pins to connect GND and Signal, the middle pins were connected together and isolated from the board with some hot glue. The glue also held the 3 connectors together.

There's a fault with one of the servos but here's my attempt to make something sound a bit musical with the remaining notes. It's not a recognisable tune!

 

Anonymous
  • in reply to ninjatrent

    For a drone you'd want to optimise for weight and also power/efficiency. That would get you the best flight times.

  • in reply to Workshopshed

    Thank you for your response.

     

              I used to have a set of drums. They were sold before I moved to California. Still regret it to this day. I hope that you might be able to find a set.

     

             It is a coincidence that you have mentioned the  Adafruit 16-Channel 12-bit PWM/Servo Driver because I happen to have a new one in the package. I have already connected an Adafruit DS3231 Precision RTC and the BME280 Temp/Baro/Humid sensor to my BBB W. I would really like to build a drone with it. I am trying to determine what is going to be the most cost effective method of bringing this idea to reality, building a platform around the BBB W or purchasing a prebuilt chassis that comes with servos, motors, and ESC. This is a rather unconventional design that I have in mind. It will require at least six standard sized hobby metal gear servos and a Brushless ESC.  Might you have any suggestions of how you would approach this sort of project?

          

    Thank you for your time in reading this and thank you for sharing your project. It is very inspiring to see such a great project accomplished with the BB Blue.

  • in reply to ninjatrent

    Sure, I was origionally going to use drums but could not find a cheap but small set. As mentioned the key thing for the blue is making sure that the servos are independently powered.

     

    If you already have a BB Black then why not use a I2C servo board? The PiConZero does 6 channels and Ada Fruit does a 16-Channel 12-bit PWM/Servo Driver.

  • in reply to Workshopshed

    Very cool project. Do you think your idea could be applied to other instruments such as a piano or drums? I was thinking about purchasing a BB Blue. Currently I have a BB Black.

  • Really awesome project!! A robot that physically performs music is such a great idea.